What About All Those Speaker Specs?

You could spend the better part of your days comparing speakers in search of the “best.” Even within a single manufacturer’s product line, there are subtle and obvious variations between speakers. Some of those variances are visible while others are guarded in the secret scrolls of specifications. With prices ranging from hundreds to many thousands of dollars, all those differences must matter, right? Yes! As you might suspect, some details matter more than others. Understanding how a speaker’s specs affect its performance is crucial to choosing the right monitors. Whether you take in music casually, listen critically for a living, or are advising someone on their next purchase, selecting speakers can make or break setups from home studios to houses of worship and beyond. As you dive into the following details about speakers and their various characteristics, please bear in mind the fact that the sound quality of speakers is directly and significantly impacted by the room in which they reside. Also, I’ll be focusing on the most common specs because there just isn’t time or space to discuss all of them in this article.

Type

Passive vs. Active:

Passive speakers require separate power amplifiers and cannot be driven directly by the line-level signals that most audio interfaces or mixing consoles send, whereas active speakers have built-in power amps and can be fed the line-level signals generated by most audio interfaces and consoles.

2-Way vs. 3-Way:

2-way speakers divide the incoming audio signal into two frequency zones, which are fed to two separate drivers. For example, a 2-way speaker may have 60 Hz to 3 kHz going to a full-range woofer, while 3 kHz to 18 kHz is directed to a tweeter.

3-way speakers divide the incoming audio signal into three frequency zones, which are fed to three separate drivers. For example, a 3-way speaker may have 60 Hz to 300 Hz going to a woofer, 300 Hz to 3 kHz sent to a midrange driver, and 3 kHz to 18 kHz routed to a tweeter.

By splitting the input signal into more frequency zones and utilizing more drivers, each speaker driver is responsible for fewer frequencies and can perform more efficiently.

Frequency Response

A speaker’s frequency response, measured in Hertz (Hz) tells you how accurately it converts the frequencies of an input signal. It’s common to see specs such as 60 Hz to 18 kHz. This means that it can transduce frequencies in that range with a certain degree of accuracy. By the numbers, frequencies outside of that range such as 30 Hz or 19 kHz will not be output from the speaker. However, the frequency range tells a very limited portion of the truth. It’s important to know the degree of accuracy, expressed as a +/- decibel variation. 20 Hz to 20 kHz (+/- 20 dB) means that there could be 20 dB differences between the input and output signals at certain frequencies. 20 Hz to 20 kHz (+/- 3 dB) means that there would only be a maximum of 3 dB differences between the input and output signals at certain frequencies. The latter is obviously more accurate.

Even more telling is a frequency response chart, which displays the decibel variations across the frequency spectrum. Such a chart allows you to see exactly where the speaker will attenuate or boost frequencies, and by how much. Frequency response charts indicate how the speaker will change the tone of the input signal. Think of it as the speaker’s equalization curve.

Maximum SPL

This indicates the highest sound pressure level the speaker can yield before a certain amount of distortion is produced. Think of it as the loudest sound you can emanate “cleanly.” Speakers with high maximum SPLs are beneficial for loud monitoring as is common for PA speakers and mid- and far-field studio monitors.

Amplifier Class (for Active Speakers)

An amplifier’s class rating denotes its topology or operating principle, which is outside the scope of this article. Instead, let’s compare their audio characteristics. The most common classes are A, B, A/B, and D. Class-A amps exhibit low distortion and noise, but aren’t very efficient. Class-B amps are very efficient, but yield more distortion and decreased signal quality. Class A/B amps are more efficient than Class-A (but less efficient than Class-B) and are low in distortion and noise. Class D amps are the most efficient, but are traditionally prone to high-frequency loss and varied audio quality, though designs are constantly improving.

Amplifier and Speaker Power

Measured in watts, this communicates the maximum electrical energy the amplifier or speaker can handle before overloading. It’s common to see ratings such as 50W, 100W, and higher. However, the wattage alone is an unfinished sentence. It was measured either in peak or RMS values, but many manufacturers don’t tell you which it was. There is a massive difference. Peak values are short duration levels, while RMS values are continuous long-duration levels. A speaker’s peak value will be significantly higher than its RMS figure. On paper, a 600W speaker seems more impressive than a 400W model, but that’s not the truth if the first speaker’s rating is 600W peak / 300W RMS while the second speaker is 400W RMS / 800W peak.

Crossover Frequency

The crossover frequency indicates the point at which the input signal is split into separate zones, which feed different amps and/or drivers. This doesn’t necessarily dictate quality, but it does tell you how frequencies will be distributed to the speaker components.

Woofer Size

Generally, larger woofers can produce lower frequencies. Thus, you might find that a certain 8" speaker’s frequency response stops at 65 Hz, while a 10" speaker may extend down to 50 Hz. Although the benefits of larger woofers are desired, their more substantial footprints aren’t always physically compatible with small spaces.

Impedance

Impedance is the level of resistance to the flow of electrical signal and is measured in Ohms. High-impedance speakers allow longer cable runs and more speakers per amp channel, but low-impedance speakers can deliver higher audio quality. The speaker impedance should match the amplifier impedance to avoid damaging the components.

Sensitivity

Sensitivity, usually measured in decibels, describes the level of output produced from a given input level. If the same input level is passed through a low-sensitivity speaker and a high-sensitivity speaker, the low-sensitivity speaker will yield a lower output level than the high-sensitivity speaker. Thus, low-sensitivity speakers usually yield lower maximum SPLs.

THD

THD is an abbreviation for Total Harmonic Distortion, which is the level of distortion produced based upon a given input signal. Assuming you’re after clean signal reproduction, lower THD values are preferred. Since THD is measured as a percentage, 0.005% would be preferred over 0.05%.

Coverage Angle

Measured in degrees, this indicates the area of audibility covered by the speaker. 90° horizontal by 90° vertical will reach more people in a variety of positions, whereas 45° horizontal by 30° vertical will allow for more accurate aim at a desired destination.

Conclusion

Hopefully, manufacturers continue to list detailed specifications and people like you continue to utilize them. Remember, the factors that most significantly affect the resulting sound quality are speaker type, frequency response, and amplifier class. Investigate further and share helpful speaker research experiences you’ve had!